The Birth Defects Research Laboratory, funded by the National Institutes of Health for 40 years, is the major national resource for the collection, description, and distribution of human conceptal tissue. During the past five years, investigators have reported at least 325 publications that have resulted from research involving specimens supplied by the Laboratory. The experience and expertise of the staff enable them to rapidly collect, identify, and process the tissues that are supplied to investigators nationally as well as internationally. Specimens are efficiently utilized as laboratory personnel are able to identify minute amounts of the fragile tissues required for individual research projects. Because organs and tissues can be identified throughout most of gestation, the Laboratory is able to serve as an economical resource for a wide range of research projects. The ability of the Laboratory to fulfill numerous tissue requests is due, in part, to longstanding relationships with regional clinics and hospitals, as well as to relatively liberal laws and attitudes in the State of Washington. Hospitals and clinics that work with the Laboratory benefit, in turn, from the Laboratory personnel's many years of experience and ability to report unusual findings. These findings may be useful for genetic counseling, confirmation of diagnostic procedures, and confirmation of the completeness of the surgical procedure. New techniques in molecular biology have sharply increased the demand for conceptal tissue, as evidenced by the number of investigators supplied during the past five years. At the same time, new medical procedures have made it increasingly difficult to collect sufficient amounts of viable tissue. Consequently, the Birth Defects Research Laboratory has become an increasingly critical resource for biomedical research. The success of the program is underscored by the many enthusiastic support letters included with this application.